I can't swear to it until I repeat the test , but my groups went from 6 inch 100 yards and me being happy to a 12 inch 100 yard o my God what happened , with just the alloy being changed . Ok there may be more to it about 6-8 weeks ago I had a few slugs that I cast out of plumbers lead with a MP 525 12 gage wad mold that shot very nice with a simple claybuster wad in a WAA hull over herco powder . Then I took off the scope and swapped the rifled barrel for a smooth bore for a while . Today I put the slug barrel back on and loaded up 10 slugs that I cast out of 50/50 coww / plumbers with the same load , and it was horrible . I am going to double check the scope mounting but I have to cast up some soft slugs to test it again . I also noticed the wads today still had the petals attached wile the previous wads cut the petals off all the way around . Possibly the soft slugs bumped up in size when fired , anyway I came home with a broken heart I knew not to mess with something that was working .